[llvm-libgcc] initial commit

Note: the term "libgcc" refers to the all of `libgcc.a`, `libgcc_eh.a`,
and `libgcc_s.so`.

Enabling libunwind as a replacement for libgcc on Linux has proven to be
challenging since libgcc_s.so is a required dependency in the [Linux
standard base][5]. Some software is transitively dependent on libgcc
because glibc makes hardcoded calls to functions in libgcc_s. For example,
the function `__GI___backtrace` eventually makes its way to a [hardcoded
dlopen to libgcc_s' _Unwind_Backtrace][1]. Since libgcc_{eh.a,s.so} and
libunwind have the same ABI, but different implementations, the two
libraries end up [cross-talking, which ultimately results in a
segfault][2].

To solve this problem, libunwind needs to build a “libgcc”. That is, link
the necessary functions from compiler-rt and libunwind into an archive
and shared object that advertise themselves as `libgcc.a`, `libgcc_eh.a`,
and `libgcc_s.so`, so that glibc’s baked calls are diverted to the
correct objects in memory. Fortunately for us, compiler-rt and libunwind
use the same ABI as the libgcc family, so the problem is solvable at the
llvm-project configuration level: no program source needs to be edited.
Thus, the end result is for a user to configure their LLVM build with a
flag that indicates they want to archive compiler-rt/unwind as libgcc.
We achieve this by compiling libunwind with all the symbols necessary
for compiler-rt to emulate the libgcc family, and then generate symlinks
named for our "libgcc" that point to their corresponding libunwind
counterparts.

We alternatively considered patching glibc so that the source doesn't
directly refer to libgcc, but rather _defaults_ to libgcc, so that a
system preferring compiler-rt/libunwind can point to these libraries
at the config stage instead. Even if we modified the Linux standard
base, this alternative won't work because binaries that are built using
libgcc will still end up having crosstalk between the differing
implementations.

This problem has been solved in this manner for [FreeBSD][3], and this
CL has been tested against [Chrome OS][4].

[1]: https://github.com/bminor/glibc/blob/master/sysdeps/arm/backtrace.c#L68
[2]: https://bugs.chromium.org/p/chromium/issues/detail?id=1162190#c16
[3]: https://github.com/freebsd/freebsd-src/tree/main/lib/libgcc_s
[4]: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2945947
[5]: https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/libgcc-s.html

Differential Revision: https://reviews.llvm.org/D108416
This commit is contained in:
Christopher Di Bella 2021-08-17 20:23:22 +00:00
parent 0c58e9f4a4
commit c5a20b5182
8 changed files with 630 additions and 1 deletions

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@ -375,7 +375,7 @@ function(add_compiler_rt_runtime name type)
if(APPLE)
# Ad-hoc sign the dylibs
add_custom_command(TARGET ${libname}
POST_BUILD
POST_BUILD
COMMAND codesign --sign - $<TARGET_FILE:${libname}>
WORKING_DIRECTORY ${COMPILER_RT_OUTPUT_LIBRARY_DIR}
)

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@ -0,0 +1,42 @@
cmake_minimum_required(VERSION 3.13.4)
if (NOT IS_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/../libunwind")
message(FATAL_ERROR "llvm-libgcc requires being built in a monorepo layout with libunwind available")
endif()
set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
list(APPEND CMAKE_MODULE_PATH
"${CMAKE_CURRENT_SOURCE_DIR}/cmake"
"${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
"${LLVM_COMMON_CMAKE_UTILS}"
"${LLVM_COMMON_CMAKE_UTILS}/Modules"
)
project(llvm-libgcc LANGUAGES C CXX ASM)
if(NOT LLVM_LIBGCC_EXPLICIT_OPT_IN)
message(FATAL_ERROR
"llvm-libgcc is not for the casual LLVM user. It is intended to be used by distro "
"managers who want to replace libgcc with compiler-rt and libunwind, but cannot "
"fully abandon the libgcc family (e.g. because they are dependent on glibc). Such "
"managers must have worked out their compatibility requirements ahead of using "
"llvm-libgcc. If you want to build llvm-libgcc, please add -DLLVM_LIBGCC_EXPLICIT_OPT_IN=Yes "
"to your CMake invocation and try again.")
endif()
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/bin")
set(COMPILER_RT_BUILD_BUILTINS On)
set(COMPILER_RT_BUILTINS_HIDE_SYMBOLS Off)
add_subdirectory("../compiler-rt" "compiler-rt")
set(LIBUNWIND_ENABLE_STATIC On)
set(LIBUNWIND_ENABLE_SHARED Off)
set(LIBUNWIND_HAS_COMMENT_LIB_PRAGMA Off)
set(LIBUNWIND_USE_COMPILER_RT On)
add_subdirectory("../libunwind" "libunwind")
add_subdirectory(lib)

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@ -0,0 +1,187 @@
.. llvm-libgcc:
===========
llvm-libgcc
===========
.. contents::
:local:
**Note that these instructions assume a Linux and bash-friendly environment.
YMMV if youre on a non Linux-based platform.**
.. _introduction:
Motivation
============
Enabling libunwind as a replacement for libgcc on Linux has proven to be
challenging since libgcc_s.so is a required dependency in the [Linux standard
base][5]. Some software is transitively dependent on libgcc because glibc makes
hardcoded calls to functions in libgcc_s. For example, the function
``__GI___backtrace`` eventually makes its way to a [hardcoded dlopen to libgcc_s'
_Unwind_Backtrace][1]. Since libgcc_{eh.a,s.so} and libunwind have the same ABI,
but different implementations, the two libraries end up [cross-talking, which
ultimately results in a segfault][2].
To solve this problem, libunwind needs libgcc "front" that is, link the
necessary functions from compiler-rt and libunwind into an archive and shared
object that advertise themselves as ``libgcc.a``, ``libgcc_eh.a``, and
``libgcc_s.so``, so that glibcs baked calls are diverted to the correct objects
in memory. Fortunately for us, compiler-rt and libunwind use the same ABI as the
libgcc family, so the problem is solvable at the llvm-project configuration
level: no program source needs to be edited. Thus, the end result is for a
distro manager to configure their LLVM build with a flag that indicates they
want to archive compiler-rt/unwind as libgcc. We achieve this by compiling
libunwind with all the symbols necessary for compiler-rt to emulate the libgcc
family, and then generate symlinks named for our "libgcc" that point to their
corresponding libunwind counterparts.
.. _alternatives
Alternatives
============
We alternatively considered patching glibc so that the source doesn't directly
refer to libgcc, but rather _defaults_ to libgcc, so that a system preferring
compiler-rt/libunwind can point to these libraries at the config stage instead.
Even if we modified the Linux standard base, this alternative won't work because
binaries that are built using libgcc will still end up having cross-talk between
the differing implementations.
.. _target audience:
Target audience
===============
llvm-libgcc is not for the casual LLVM user. It is intended to be used by distro
managers who want to replace libgcc with compiler-rt and libunwind, but cannot
fully abandon the libgcc family (e.g. because they are dependent on glibc). Such
managers must have worked out their compatibility requirements ahead of using
llvm-libgcc.
.. _cmake options:
CMake options
=============
.. option:: `LLVM_LIBGCC_EXPLICIT_OPT_IN`
**Required**
Since llvm-libgcc is such a fundamental, low-level component, we have made it
difficult to accidentally build, by requiring you to set an opt-in flag.
.. _Building llvm-libgcc
Building llvm-libgcc
--------------------
The first build tree is a mostly conventional build tree and gets you a Clang
build with these compiler-rt symbols exposed.
.. code-block:: bash
# Assumes $(PWD) is /path/to/llvm-project
$ cmake -GNinja -S llvm -B build-primary \
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_CROSSCOMPILING=On \
-DCMAKE_INSTALL_PREFIX=/tmp/aarch64-unknown-linux-gnu \
-DLLVM_ENABLE_PROJECTS='clang' \
-DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;llvm-libgcc" \
-DLLVM_TARGETS_TO_BUILD=AArch64 \
-DLLVM_DEFAULT_TARGET_TRIPLE=aarch64-unknown-linux-gnu \
-DLLVM_LIBGCC_EXPLICIT_OPT_IN=Yes
$ ninja -C build-primary install
It's very important to notice that neither ``compiler-rt``, nor ``libunwind``,
are listed in ``LLVM_ENABLE_RUNTIMES``. llvm-libgcc makes these subprojects, and
adding them to this list will cause you problems due to there being duplicate
targets. As such, configuring the runtimes build will reject explicitly mentioning
either project with ``llvm-libgcc``.
To avoid issues when building with ``-DLLVM_ENABLE_RUNTIMES=all``, ``llvm-libgcc``
is not included, and all runtimes targets must be manually listed.
## Verifying your results
This gets you a copy of libunwind with the libgcc symbols. You can verify this
using ``readelf``.
.. code-block:: bash
$ llvm-readelf -W --dyn-syms "${LLVM_LIBGCC_SYSROOT}/lib/libunwind.so" | grep FUNC | grep GCC_3.0
Roughly sixty symbols should appear, all suffixed with ``@@GCC_3.0``. You can
replace ``GCC_3.0`` with any of the supported version names in the version
script youre exporting to verify that the symbols are exported.
.. _supported platforms:
Supported platforms
===================
llvm-libgcc currently supports the following target triples:
* ``aarch64-*-*-*``
* ``armv7a-*-*-gnueabihf``
* ``i386-*-*-*``
* ``x86_64-*-*-*``
If you would like to support another triple (e.g. ``powerpc64-*-*-*``), you'll
need to generate a new version script, and then edit ``lib/gcc_s.ver``.
.. _Generating a new version script
Generating a new version script
-------------------------------
To generate a new version script, we need to generate the list of symbols that
exist in the set (``clang-builtins.a`` ``libunwind.a``) ∩ ``libgcc_s.so.1``.
The prerequisites for generating a version script are a binaries for the three
aforementioned libraries targeting your architecture (without having built
llvm-libgcc).
Once these libraries are in place, to generate a new version script, run the
following command.
.. code-block:: bash
/path/to/llvm-project
$ export ARCH=powerpc64
$ llvm/tools/llvm-libgcc/generate_version_script.py \
--compiler_rt=/path/to/libclang_rt.builtins-${ARCH}.a \
--libunwind=/path/to/libunwind.a \
--libgcc_s=/path/to/libgcc_s.so.1 \
--output=${ARCH}
This will generate a new version script a la
``/path/to/llvm-project/llvm/tools/llvm-libgcc/gcc_s-${ARCH}.ver``, which we use
in the next section.
.. _Editing ``lib/gcc_s.ver``
Editing ``lib/gcc_s.ver``
-------------------------
Our freshly generated version script is unique to the specific architecture that
it was generated for, but a lot of the symbols are shared among many platforms.
As such, we don't check in unique version scripts, but rather have a single
version script that's run through the C preprocessor to prune symbols we won't
be using in ``lib/gcc_s.ver``.
Working out which symbols are common is largely a manual process at the moment,
because some symbols may be shared across different architectures, but not in
the same versions of libgcc. As such, a symbol appearing in ``lib/gcc_s.ver``
doesn't guarantee that the symbol is available for our new architecture: we need
to verify that the versions are the same, and if they're not, add the symbol to
the new version section, with the appropriate include guards.
There are a few macros that aim to improve readability.
* ``ARM_GNUEABIHF``, which targets exactly ``arm-*-*-gnueabihf``.
* ``GLOBAL_X86``, which should be used to target both x86 and x86_64, regardless
of the triple.
* ``GLOBAL_32BIT``, which is be used to target 32-bit platforms.
* ``GLOBAL_64BIT``, which is be used to target 64-bit platforms.

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@ -0,0 +1,131 @@
#!/usr/bin/env python3
# Generates a version script for an architecture so that it can be incorporated
# into gcc_s.ver.
from collections import defaultdict
from itertools import chain
import argparse, subprocess, sys, os
def split_suffix(symbol):
"""
Splits a symbol such as `__gttf2@GCC_3.0` into a triple representing its
function name (__gttf2), version name (GCC_3.0), and version number (300).
The version number acts as a priority. Since earlier versions are more
accessible and are likely to be used more, the lower the number is, the higher
its priortiy. A symbol that has a '@@' instead of '@' has been designated by
the linker as the default symbol, and is awarded a priority of -1.
"""
if '@' not in symbol:
return None
data = [i for i in filter(lambda s: s, symbol.split('@'))]
_, version = data[-1].split('_')
version = version.replace('.', '')
priority = -1 if '@@' in symbol else int(version + '0' *
(3 - len(version)))
return data[0], data[1], priority
def invert_mapping(symbol_map):
"""Transforms a map from Key->Value to Value->Key."""
store = defaultdict(list)
for symbol, (version, _) in symbol_map.items():
store[version].append(symbol)
result = []
for k, v in store.items():
v.sort()
result.append((k, v))
result.sort(key=lambda x: x[0])
return result
def intersection(llvm, gcc):
"""
Finds the intersection between the symbols extracted from compiler-rt.a/libunwind.a
and libgcc_s.so.1.
"""
common_symbols = {}
for i in gcc:
suffix_triple = split_suffix(i)
if not suffix_triple:
continue
symbol, version_name, version_number = suffix_triple
if symbol in llvm:
if symbol not in common_symbols:
common_symbols[symbol] = (version_name, version_number)
continue
if version_number < common_symbols[symbol][1]:
common_symbols[symbol] = (version_name, version_number)
return invert_mapping(common_symbols)
def find_function_names(path):
"""
Runs readelf on a binary and reduces to only defined functions. Equivalent to
`llvm-readelf --wide ${path} | grep 'FUNC' | grep -v 'UND' | awk '{print $8}'`.
"""
result = subprocess.run(args=['llvm-readelf', '-su', path],
capture_output=True)
if result.returncode != 0:
print(result.stderr.decode('utf-8'), file=sys.stderr)
sys.exit(1)
stdout = result.stdout.decode('utf-8')
stdout = filter(lambda x: 'FUNC' in x and 'UND' not in x,
stdout.split('\n'))
stdout = chain(
map(lambda x: filter(None, x), (i.split(' ') for i in stdout)))
return [list(i)[7] for i in stdout]
def to_file(versioned_symbols):
path = f'{os.path.dirname(os.path.realpath(__file__))}/new-gcc_s-symbols'
with open(path, 'w') as f:
f.write('Do not check this version script in: you should instead work '
'out which symbols are missing in `lib/gcc_s.ver` and then '
'integrate them into `lib/gcc_s.ver`. For more information, '
'please see `doc/LLVMLibgcc.rst`.\n')
for version, symbols in versioned_symbols:
f.write(f'{version} {{\n')
for i in symbols:
f.write(f' {i};\n')
f.write('};\n\n')
def read_args():
parser = argparse.ArgumentParser()
parser.add_argument('--compiler_rt',
type=str,
help='Path to `libclang_rt.builtins-${ARCH}.a`.',
required=True)
parser.add_argument('--libunwind',
type=str,
help='Path to `libunwind.a`.',
required=True)
parser.add_argument(
'--libgcc_s',
type=str,
help=
'Path to `libgcc_s.so.1`. Note that unlike the other two arguments, this is a dynamic library.',
required=True)
return parser.parse_args()
def main():
args = read_args()
llvm = find_function_names(args.compiler_rt) + find_function_names(
args.libunwind)
gcc = find_function_names(args.libgcc_s)
versioned_symbols = intersection(llvm, gcc)
# TODO(cjdb): work out a way to integrate new symbols in with the existing
# ones
to_file(versioned_symbols)
if __name__ == '__main__':
main()

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@ -0,0 +1,85 @@
include(CheckLibraryExists)
include(GNUInstallDirs)
string(REPLACE "-Wl,-z,defs" "" CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS}")
add_custom_target(gcc_s_ver ALL DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver")
set(LLVM_LIBGCC_GCC_S_VER "${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver")
add_custom_target(gcc_s.ver ALL
DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/gcc_s.ver"
COMMAND
"${CMAKE_C_COMPILER}"
"-E"
"-xc" "${CMAKE_CURRENT_SOURCE_DIR}/gcc_s.ver"
"-o" "${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver"
)
set_target_properties(gcc_s.ver PROPERTIES
OUTPUT_PATH "${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver")
add_library(libgcc_s SHARED blank.c)
add_dependencies(libgcc_s gcc_s_ver)
set_target_properties(libgcc_s
PROPERTIES
LINKER_LANGUAGE C
OUTPUT_NAME "unwind"
VERSION "1.0"
SOVERSION "1"
POSITION_INDEPENDENT_CODE ON)
string(REGEX MATCH "[^-]+" LLVM_LIBGCC_TARGET_ARCH ${CMAKE_C_COMPILER_TARGET})
target_link_libraries(libgcc_s PRIVATE
$<TARGET_OBJECTS:unwind_static>
$<TARGET_OBJECTS:clang_rt.builtins-${LLVM_LIBGCC_TARGET_ARCH}>
)
target_link_options(libgcc_s PRIVATE
-nostdlib
-Wl,--version-script,$<TARGET_PROPERTY:gcc_s.ver,OUTPUT_PATH>)
check_library_exists(m sin "" LLVM_LIBGCC_HAS_LIBM)
target_link_libraries(libgcc_s PRIVATE
$<$<BOOL:LLVM_LIBGCC_HAS_LIBM>:m>
c
)
get_filename_component(LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT "${CMAKE_INSTALL_PREFIX}/${LIBUNWIND_INSTALL_LIBRARY_DIR}" ABSOLUTE)
#string(REPLACE "${CMAKE_INSTALL_FULL_LIBDIR}/" "" LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT "${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}")
install(TARGETS libgcc_s
LIBRARY DESTINATION "${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}" COMPONENT unwind
ARCHIVE DESTINATION "${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}" COMPONENT unwind
RUNTIME DESTINATION bin COMPONENT unwind)
get_compiler_rt_install_dir(${LLVM_LIBGCC_TARGET_ARCH} install_dir_builtins)
string(REGEX REPLACE "^lib/" "" install_dir_builtins "${install_dir_builtins}")
string(FIND "${install_dir_builtins}" "clang" install_path_contains_triple)
if(install_path_contains_triple EQUAL -1)
set(builtins_suffix "-${LLVM_LIBGCC_TARGET_ARCH}")
else()
string(PREPEND install_dir_builtins "../")
endif()
install(CODE "execute_process(
COMMAND \"\${CMAKE_COMMAND}\" -E
create_symlink ${install_dir_builtins}/libclang_rt.builtins${builtins_suffix}.a libgcc.a
WORKING_DIRECTORY \"\$ENV{DESTDIR}${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}\")"
COMPONENT unwind)
install(CODE "execute_process(
COMMAND \"\${CMAKE_COMMAND}\" -E
create_symlink libunwind.a libgcc_eh.a
WORKING_DIRECTORY \"\$ENV{DESTDIR}${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}\")"
COMPONENT unwind)
install(CODE "execute_process(
COMMAND \"\${CMAKE_COMMAND}\" -E
create_symlink libunwind.so libgcc_s.so.1.0
WORKING_DIRECTORY \"\$ENV{DESTDIR}${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}\")"
COMPONENT unwind)
install(CODE "execute_process(
COMMAND \"\${CMAKE_COMMAND}\" -E
create_symlink libgcc_s.so.1.0 libgcc_s.so.1
WORKING_DIRECTORY \"\$ENV{DESTDIR}${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}\")"
COMPONENT unwind)
install(CODE "execute_process(
COMMAND \"\${CMAKE_COMMAND}\" -E
create_symlink libgcc_s.so.1 libgcc_s.so
WORKING_DIRECTORY \"\$ENV{DESTDIR}${LLVM_LIBGCC_LIBUNWIND_STATIC_ROOT}\")"
COMPONENT unwind)

0
llvm-libgcc/lib/blank.c Normal file
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@ -0,0 +1,167 @@
// Detect if we're using arm-*-*-gnueabihf
#if defined(__arm__) && \
defined(__ARM_ARCH_7A__) && defined(__ARM_EABI__) && \
defined(__ARM_FP) && (__ARM_FP >= 0x04)
#define ARM_GNUEABIHF
#endif
#if !defined(__x86_64__) && \
!defined(__aarch64__) && \
!defined(__i386__) && \
!defined(ARM_GNUEABIHF)
#error The only platforms that are currently supported are x86_64, i386, arm-gnueabihf, and aarch64.
#endif
#if defined(__x86_64__) || defined(__i386__)
#define GLOBAL_X86
#endif
#if __SIZEOF_POINTER__ >= 8
#define GLOBAL_64BIT
#else
#define GLOBAL_32BIT
#endif
GCC_3.0 {
__absvdi2; __absvsi2; __addvdi3; __addvsi3; __clear_cache; __ffsdi2;
__fixunsdfdi; __fixunssfdi; __mulvdi3; __mulvsi3; __negvdi2; __negvsi2;
__subvdi3; __subvsi3;
_Unwind_DeleteException;
_Unwind_ForcedUnwind;
_Unwind_GetDataRelBase;
_Unwind_GetLanguageSpecificData;
_Unwind_GetRegionStart;
_Unwind_GetTextRelBase;
_Unwind_RaiseException;
_Unwind_Resume;
};
GCC_3.3 { _Unwind_GetCFA; _Unwind_Resume_or_Rethrow; };
GCC_3.3.1 { __gcc_personality_v0; };
GCC_3.4 { __clzdi2; __ctzdi2; __paritydi2; __popcountdi2; };
GCC_3.4.2 { __enable_execute_stack; };
GCC_4.0.0 { __divdc3; __divsc3; __muldc3; __mulsc3; __powidf2; __powisf2; };
GCC_4.3.0 { __bswapdi2; __bswapsi2; __emutls_get_address; };
#if defined(GLOBAL_32BIT)
GCC_3.0 {
__ashldi3; __ashrdi3; __cmpdi2; __fixdfdi; __fixsfdi; __fixunsdfsi;
__fixunssfsi; __floatdidf; __floatdisf; __lshrdi3; __muldi3; __negdi2;
__ucmpdi2; __udivmoddi4;
};
GCC_3.4 { __clzsi2; __ctzsi2; __paritysi2; __popcountsi2; };
GCC_4.2.0 { __floatundidf; __floatundisf; };
GCC_4.3.0 { __ffssi2; };
GCC_7.0.0 { __divmoddi4; };
GLIBC_2.0 { __divdi3; __moddi3; __udivdi3; __umoddi3; };
#elif defined(GLOBAL_64BIT)
GCC_3.0 {
__ashlti3; __ashrti3; __cmpti2; __divti3; __ffsti2; __fixdfti;
__fixsfti; __fixunssfti; __floattidf; __lshrti3; __modti3; __multi3;
__negti2; __ucmpti2; __udivmodti4; __udivti3; __umodti3; __fixunsdfti;
__floattisf;
};
GCC_3.4 { __clzti2; __ctzti2; __parityti2; __popcountti2; };
GCC_3.4.4 { __absvti2; __addvti3; __mulvti3; __negvti2; __subvti3; };
GCC_4.2.0 { __floatuntidf; __floatuntisf; };
GCC_7.0.0 { __divmodti4; };
#endif
#if defined(GLOBAL_X86)
GCC_3.0 {
__deregister_frame_info_bases; __fixunsxfdi; __register_frame_info_bases;
__register_frame_info_table_bases;
};
GCC_4.0.0 { __divxc3; __mulxc3; __powixf2; };
GCC_4.8.0 { __cpu_indicator_init; };
#endif
#if !defined(ARM_GNUEABIHF)
GCC_3.0 {
_Unwind_Find_FDE; _Unwind_GetGR; _Unwind_GetIP; _Unwind_SetGR; _Unwind_SetIP;
};
GCC_3.3 { _Unwind_Backtrace; _Unwind_FindEnclosingFunction; };
GCC_4.2.0 { _Unwind_GetIPInfo; };
#else // defined(ARM_GNUEABIHF)
GCC_3.0 {
__adddf3; __addsf3; __divdf3; __divsf3; __divsi3; __eqdf2;
__eqsf2; __extendsfdf2; __fixdfsi; __fixsfsi; __floatsidf; __floatsisf;
__gedf2; __gesf2; __gtdf2; __gtsf2; __ledf2; __lesf2;
__ltdf2; __ltsf2; __modsi3; __muldf3; __mulsf3; __nedf2;
__negdf2; __negsf2; __nesf2; __subdf3; __subsf3; __truncdfsf2;
__udivsi3; __umodsi3;
};
GCC_3.3.4 { __unorddf2; __unordsf2; };
GCC_3.5 {
__aeabi_cdcmpeq; __aeabi_cdcmple; __aeabi_cdrcmple; __aeabi_cfcmpeq;
__aeabi_cfcmple; __aeabi_cfrcmple; __aeabi_d2f; __aeabi_d2iz;
__aeabi_d2lz; __aeabi_d2uiz; __aeabi_d2ulz; __aeabi_dadd;
__aeabi_dcmpeq; __aeabi_dcmpge; __aeabi_dcmpgt; __aeabi_dcmple;
__aeabi_dcmplt; __aeabi_dcmpun; __aeabi_ddiv; __aeabi_dmul;
__aeabi_dneg; __aeabi_drsub; __aeabi_dsub; __aeabi_f2d;
__aeabi_f2iz; __aeabi_f2lz; __aeabi_f2uiz; __aeabi_f2ulz;
__aeabi_fadd; __aeabi_fcmpeq; __aeabi_fcmpge; __aeabi_fcmpgt;
__aeabi_fcmple; __aeabi_fcmplt; __aeabi_fcmpun; __aeabi_fdiv;
__aeabi_fmul; __aeabi_fneg; __aeabi_frsub; __aeabi_fsub;
__aeabi_i2d; __aeabi_i2f; __aeabi_idiv; __aeabi_idiv0;
__aeabi_idivmod; __aeabi_l2d; __aeabi_l2f; __aeabi_lasr;
__aeabi_lcmp; __aeabi_ldiv0; __aeabi_ldivmod; __aeabi_llsl;
__aeabi_llsr; __aeabi_lmul; __aeabi_ui2d; __aeabi_ui2f;
__aeabi_uidiv; __aeabi_uidivmod; __aeabi_ul2d; __aeabi_ul2f;
__aeabi_ulcmp; __aeabi_uldivmod; __aeabi_unwind_cpp_pr0;
__aeabi_unwind_cpp_pr1; __aeabi_unwind_cpp_pr2;
__gnu_unwind_frame;
_Unwind_Complete;
_Unwind_VRS_Get;
_Unwind_VRS_Pop;
_Unwind_VRS_Set;
};
GCC_4.2.0 { __floatunsidf; __floatunsisf; };
GCC_4.3.0 { _Unwind_Backtrace; };
#endif
#if defined(__aarch64__)
GCC_3.0 {
__addtf3; __divtf3; __eqtf2; __extenddftf2; __extendsftf2;
__fixtfdi; __fixtfsi; __fixtfti; __fixunstfdi; __fixunstfsi;
__fixunstfti; __floatditf; __floatsitf; __floattitf; __getf2;
__gttf2; __letf2; __lttf2; __multf3; __netf2;
__subtf3; __trunctfdf2; __trunctfsf2;
};
GCC_4.0.0 { __powitf2; __divtc3; __multc3; };
GCC_4.2.0 { __floatunditf; __floatunsitf; __floatuntitf; };
GCC_4.5.0 { __unordtf2; };
#endif
#if defined(__aarch64__) || defined(__i386__)
GLIBC_2.0 { __deregister_frame; __register_frame; };
#endif
#if defined(__i386__)
GCC_3.0 { __fixunsxfsi; __fixxfdi; __floatdixf; };
GCC_4.2.0 { __floatundixf; };
GLIBC_2.0 {
__register_frame_info; __register_frame_info_table; __register_frame_table;
__deregister_frame_info;
};
#endif
#if defined(__x86_64__)
GCC_3.0 {
__register_frame_info; __register_frame_info_table; __register_frame_table;
__deregister_frame; __deregister_frame_info; __register_frame;
__fixunsxfti; __fixxfti; __floattixf;
};
GCC_4.2.0 { __floatuntixf; };
GCC_4.3.0 { __divtc3; __multc3; };
#endif

View File

@ -178,6 +178,23 @@ if(LLVM_INCLUDE_TESTS)
set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
endif()
# llvm-libgcc incorporates both compiler-rt and libunwind as subprojects with very
# specific flags, which causes clashes when they're independently built too.
if("llvm-libgcc" IN_LIST runtimes)
if("compiler-rt" IN_LIST runtimes OR "compiler-rt" IN_LIST LLVM_ENABLE_PROJECTS)
message(FATAL_ERROR
"Attempting to build both compiler-rt and llvm-libgcc will cause irreconcilable "
"target clashes. Please choose one or the other, but not both.")
endif()
if("libunwind" IN_LIST runtimes)
message(
FATAL_ERROR
"Attempting to build both libunwind and llvm-libgcc will cause irreconcilable "
"target clashes. Please choose one or the other, but not both.")
endif()
endif()
# We do this in two loops so that HAVE_* is set for each runtime before the
# other runtimes are added.
foreach(entry ${runtimes})